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diff --git a/geom_matching/wasserstein/include/spdlog/details/mpmc_bounded_q.h b/geom_matching/wasserstein/include/spdlog/details/mpmc_bounded_q.h
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+/*
+A modified version of Bounded MPMC queue by Dmitry Vyukov.
+
+Original code from:
+http://www.1024cores.net/home/lock-free-algorithms/queues/bounded-mpmc-queue
+
+licensed by Dmitry Vyukov under the terms below:
+
+Simplified BSD license
+
+Copyright (c) 2010-2011 Dmitry Vyukov. All rights reserved.
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+1. Redistributions of source code must retain the above copyright notice, this list of
+conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list
+of conditions and the following disclaimer in the documentation and/or other materials
+provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY DMITRY VYUKOV "AS IS" AND ANY EXPRESS OR IMPLIED
+WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+SHALL DMITRY VYUKOV OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+The views and conclusions contained in the software and documentation are those of the authors and
+should not be interpreted as representing official policies, either expressed or implied, of Dmitry Vyukov.
+*/
+
+/*
+The code in its current form adds the license below:
+
+Copyright(c) 2015 Gabi Melman.
+Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+*/
+
+#pragma once
+
+#include "spdlog/common.h"
+
+#include <atomic>
+#include <utility>
+
+namespace spdlog
+{
+namespace details
+{
+
+template<typename T>
+class mpmc_bounded_queue
+{
+public:
+
+    using item_type = T;
+    mpmc_bounded_queue(size_t buffer_size)
+        :max_size_(buffer_size),
+         buffer_(new cell_t [buffer_size]),
+         buffer_mask_(buffer_size - 1)
+    {
+        //queue size must be power of two
+        if(!((buffer_size >= 2) && ((buffer_size & (buffer_size - 1)) == 0)))
+            throw spdlog_ex("async logger queue size must be power of two");
+
+        for (size_t i = 0; i != buffer_size; i += 1)
+            buffer_[i].sequence_.store(i, std::memory_order_relaxed);
+        enqueue_pos_.store(0, std::memory_order_relaxed);
+        dequeue_pos_.store(0, std::memory_order_relaxed);
+    }
+
+    ~mpmc_bounded_queue()
+    {
+        delete [] buffer_;
+    }
+
+
+    bool enqueue(T&& data)
+    {
+        cell_t* cell;
+        size_t pos = enqueue_pos_.load(std::memory_order_relaxed);
+        for (;;)
+        {
+            cell = &buffer_[pos & buffer_mask_];
+            size_t seq = cell->sequence_.load(std::memory_order_acquire);
+            intptr_t dif = (intptr_t)seq - (intptr_t)pos;
+            if (dif == 0)
+            {
+                if (enqueue_pos_.compare_exchange_weak(pos, pos + 1, std::memory_order_relaxed))
+                    break;
+            }
+            else if (dif < 0)
+            {
+                return false;
+            }
+            else
+            {
+                pos = enqueue_pos_.load(std::memory_order_relaxed);
+            }
+        }
+        cell->data_ = std::move(data);
+        cell->sequence_.store(pos + 1, std::memory_order_release);
+        return true;
+    }
+
+    bool dequeue(T& data)
+    {
+        cell_t* cell;
+        size_t pos = dequeue_pos_.load(std::memory_order_relaxed);
+        for (;;)
+        {
+            cell = &buffer_[pos & buffer_mask_];
+            size_t seq =
+                cell->sequence_.load(std::memory_order_acquire);
+            intptr_t dif = (intptr_t)seq - (intptr_t)(pos + 1);
+            if (dif == 0)
+            {
+                if (dequeue_pos_.compare_exchange_weak(pos, pos + 1, std::memory_order_relaxed))
+                    break;
+            }
+            else if (dif < 0)
+                return false;
+            else
+                pos = dequeue_pos_.load(std::memory_order_relaxed);
+        }
+        data = std::move(cell->data_);
+        cell->sequence_.store(pos + buffer_mask_ + 1, std::memory_order_release);
+        return true;
+    }
+
+    size_t approx_size()
+    {
+        size_t first_pos = dequeue_pos_.load(std::memory_order_relaxed);
+        size_t last_pos = enqueue_pos_.load(std::memory_order_relaxed);
+        if (last_pos <= first_pos)
+            return 0;
+        auto size = last_pos - first_pos;
+        return size < max_size_ ? size : max_size_;
+    }
+
+private:
+    struct cell_t
+    {
+        std::atomic<size_t>   sequence_;
+        T                     data_;
+    };
+
+    size_t const max_size_;
+
+    static size_t const     cacheline_size = 64;
+    typedef char            cacheline_pad_t [cacheline_size];
+
+    cacheline_pad_t         pad0_;
+    cell_t* const           buffer_;
+    size_t const            buffer_mask_;
+    cacheline_pad_t         pad1_;
+    std::atomic<size_t>     enqueue_pos_;
+    cacheline_pad_t         pad2_;
+    std::atomic<size_t>     dequeue_pos_;
+    cacheline_pad_t         pad3_;
+
+    mpmc_bounded_queue(mpmc_bounded_queue const&) = delete;
+    void operator= (mpmc_bounded_queue const&) = delete;
+};
+
+} // ns details
+} // ns spdlog